Mechanical shaver head having cutter bars of reduced thickness



March 25, 1958 P. KOBLER 2,827,693

MECHANICAL SHAVER HEAD HAVING CUTTER BARS OF REDUCED THICKNESS FiledNov. 9, 1953 Has ' ]NVENTOR.. v k

into the cutting slots and the strength of the cutting niterl tatesPatent strength of the cutting member as its breadth is only a fractionnot more than one-tlird of the breadth of 2,s27,es3

the most efiective cutting zone. It has been found that MECHANICALSHAVER HEAD HA I G CUTTER the wear of the cutting member due to long useof the BARS {)F REDUCED THICKNESS 5 apparatus extends to the mentionedthinned portion to a small extent onl If, for exam le, the re-shavingPaul Kgbler Lynbmsk to Victor Kobier zone is worn out trim a thicknessof 0.l mm. to a thickand Kobse! bath of lunch switzefland ness of 0.07mm. the thinned portion will practically ppli ation November 9, 1953,Serial No.391,003 keep its thickness of 0.02 mm. so that the strength ofthe shearhead is not im aired. The reason therefor lies Claims pnomyapplication Swltzefland June 1953 in the fact that the thinn ed portion,due to its small thick- 2 Cl (CL 30 ness is resilient and escapes theattack of the inner cutting member. It has further been found thatapparatus, the cutting member of which has a thickness of 0.06 mm. TapPhcatlen is a Continuation-impart Of y PP or less over a larger regionof its cutting zone and at Canon Serial fi y 9, 1952, r S earleast inthe most effective cutting region, are rapidly head for y Shaving Appratus. now Patent No. worn out to the thickness of ca. 0.04 mm., whichis abso- 39,380, dated March 27, 1956. lutely necessary to give thenecessary strength to the The present invention relates to an electricaldry shavshearhead.

3 ppa of h yp having at leest one Sheafheed If, one the other hand, thethickness of the most effeccompflslng a siatlellery Outer Cuttlhg memberand an tive half of the cutting portion decreases continuously innereutthlg member fecipfoeahle Within and i i iin direction of the middleof said portion, such apparatus nally of said outer cutting member forcooperation thereha no broad pre-shaving zone as the skin entersrelawith. tively deeply into the cutting slots. This drawback too, As Isknown In the an, the e g 0f the l is avoided in the apparatus of thepresent invention. is effected, in apparatus of the mentioned closedtype, The benefit of the invention are obtained more espesuccessivelyover the whole breadth of the shearhead, namely in apparatus of thesieve construction by the successive openings of the sieve and inapparatus of the slot construction by increasing entering of the skininto cially by providing heavier and thus, stronger parts immediatelyadjacent the inner portion of the shear-head used for close shaving, inthe longitudinal direction as well as in the transverse direction.

the slots. i The features of novelty of the invention are of especial It1s one Of the ohleets 0f the Pf lhvefltlento advantage when they arelocated toward the center of a provide an apparatus of theaforementioned type, in which curved shear-head.

the shearhead is provided with a broadest possible preshaving zone, inwhich the thickness of the outer cutting member is kept as small aspossible to enable a closest possible shave without irritation of theskin by the inner cutting member, and without unduly reducing theresistance to wear and tear of the shearhead. Thereby the cutting regionis of such arrangement that perfect close shaving is possible in spiteof the relatively great thickness of the greater part of outer cuttingmember. According to this invention this aim is attained in that Otherobjects and advantages of the invention will become apparent from thedescription now to follow of a preferred embodiment thereof, in whichreference will be had to the accompanying drawing, in which:

Fig. 1 is a longitudinal section through a shearhead of a dry shavingapparatus according to the invention;

Fig. 2 is a plan view of the most effective half of the cutting zone ofthe apparatus at an enlarged scale;

Fig. 3 shows in perspective part of the apparatus, with portions thereofcut away to show its transverse section; the cutting zone of the outercutting member has an at Figs, 4 and 5 Show at an enlarggd scale partialcrossleast substantially constant thickness over at least half Sectionsalong li IV IV and V-V, respectively, of of its extent, whereby anelongated, thinned portion is Fi 2; provided, in the most efiectivezone, the breadth of said Fi 6, 7 d 3 a e longitudinal sections, takenon thinned Portion being only a fraction of not more than lines VI-VI,VII-VII and VIII-VIII, respectively of one-third of the correspondingdimension of said most Fi 4 d 5; efiective zone and further beingelevated with respect to Fi 9 i a l iew of the most efiective half ofthe the immediately adjacent portion of the cutting member. cutting Zonef an lt rnative embodiment;

Because of the aforementioned practically constant Fig 10 is a Plan Viewf a dry Shaving apparatus h thickness of the greater part of the mostefiective part i three h h d 0f the eutfihg Portion the skill isPrevented from enter Fig. 11 is a plan view of a further embodiment of aing too deeply into the cutting slots, whereas, in known Shearheadaccording to hi i i n, constructions, in which the thickness of thecutting mem- As shown i Fi 1 to 8, th elongated shearhead of herdecreases progressively, such is v y Often the Case, a dry shavingapparatus comprises a base piece I mounted and causes irritation of theskin or even injuries. The by Sockets 2 on h housing 3 f the apparatus.This thinned QOIU'OII, P in widen-Shaving Zone base piece carries anouter cutting member 4 which is in Ciefs P s a Perfect close shavlllgiWhlle at the same the general form of a longitudinally arched invertedU- time it 18 so narrow that the skin cannot enter too deeply Shapedchannel and h ll l flange of hi h are riveted at 5 to the base piece 1.In its top portion, the outer cutting member is provided with a seriesof equidistant transverse slots 6 leaving between them small bridges 7.

member is not impaired. Due to the elevation of the thinned zone overthe adjacent portion of the cutting member a better support of said zoneis attained so that it cannot be forced in. The mentioned elevation maybe The upper side, outwardly vaulted i longitudinal 1- Obtained yVaulting the Cutting Portion y arranging rection, of the base piece 1has a longitudinal groove 8 the thinned Portion in the Crest of aroof-shaped vWtlihg guiding an inner cutting member 9 in the shape of aring portion. Th PIE- ha ing Z P mi s Close shaving segment having anenlarged rim into which are cut equieven with an approximative constantthickness of 0.1 mm. distant transverse slots 11 leaving between them aseries as long as the thinned portionhas a thickness of 0.02 of teeth12. The top face of these teeth 12 conforms to mm. only. This thinnedportion does not impair the the inner face of the bridges 7 left betweenthe slots 6 and is wider, in a longitudinal direction of member 9, thanthe said slots 6 so that the teeth 12 cannot engage the slots 6 and theinner cutting member 9 is maintained in its guiding groove 8 by theouter cutting member but capable of longitudinal motion. along'thelatters inner face. Moreover, the inner cutting member has'a recess 13engaged by an actuating lever 14 extending through a wide opening 15 inthe base piece 1. This actuating lever 14 is pivoted on a pin (notshown) in the housing 3 and in operation is oscillated by an electricmotor and suitable transmission means (not shown) lodged in the saidhousing. 7

Thus, at operation of the apparatus, the inner cutting member 9 will bereciprocated along the inner-face of 'the outer cutting member 4 and anyhair which extends into the'slots 11 through the slots 6 when theseslots registerwill be cut olf between the adjacent bridge 7 and teeth 12as the inner cuttingmember 9 moves with reaspect to the outer zone 4. ,7

Referring now particularly. to Figs. 4 and which show transversesections on section lines IV-JV and V- V, respectively, 'of Fig. 2, ofthe top portion ofthe outer cutting member 4, at spaced points thereof,the said outer cutting member 4 has two inner surfaces 17 defined andrepresented by a pair of straight lines intersecting each other at 18,at an obtuse angle. Further, the outer cutting member 4 has two outersurfaces 19 also represented or defined by a pair of straight lineswhich are parallel to those representing the inner surfaces 17. In Fig.5, which is a cross-section taken'through an end portion of member 4,the lines indicating the surfaces 19 intersect eachother at 20, whichindicates an obtuse edge along which the surfaces 19 meet each other. 7

. At the central portion of outer cutter member 4, however the surfaces19 do not meet but, in between them there is a third outer surface 21aFig. 2, which is represented .in transverse section by a straight'linein Fig. 4.

Therebythe arrangement is such that the smallest distance between thesurface 21a and the said point 18 is smaller than that between the innerand outer surfaces 17 and 19, respectively measured in the. samedirection. It will be understood that all the surfaces 17, 19 and 21aare interrupted from place to place by the slots 6. Of course thetransverse section of the outer surface 21 could also be an outwardly orinwardly curved line.

Figs. 6 to 8 are sections taken longitudinally through various portionsofthe outer cutting member to show the cross-section of the bridges 7.Fig. 6 represents a normal cross-section through three bridges 7 of thecutting mem-ber 4. The edges 22 of the bridges 7 at which the slots 6meet the outer surfaces 19 are rounded, while the edges 23 at hich" theslots 6 meet the inner surfaces 17 are sharp; these sharp edges 23. are,in fact, the cutting edges of the outer cutting member Fig. 7 is'alongitudinal section of theouter cutting member, showing three bridges 7in cross-section and applying only to the end portions, having thetransverse section shown in Fig; 5. Fig. 7 differs from Fig. 6 in thatits plane passes through the edges 1% and 28 (Fig. 5), i. el obliquelywith respectto the surfaces 17 and 19. Therefore, the height of thebridges 7 is greater in Fig. 7 than in Fig. 6, but otherwise the twofigures are identical. Fig. 8 is a longitudinal section similar to thatof Fig. 7 but taken in the central portion of member 4 to which Fig. 4applies. The height of the bridges 7 in this section, which is thedistance between the surface 21a and -the edge 18, therefore is-smallerthan in the section of Fig." 7. The height of thebrid ges 7 in thesection according to Fig. 8 is smaller than the height of the bridgesinthe section according to Fig. 6. V 7 V V t is As shown in Fig. 8, theedges 24 of the bridges 7 at which theslots 6 meet "the outer surface21a are sharp. This will conveniently'be achieved by :first grinding thesurfaces 19 and the slots 6 withtheir common rounded edges 22,throughout thelengtlr of the cutting member 4,

5 the sharp edges 24 are formed.

In an alternative embodiment shown in plan view in Fig. 9, an outersurface 21b of outer cutter 4a is provided which extends only aportionof the length of the cutting member, has a longitudinal curvaturewhich is less pronounced than that of the remainder of the outensu'rfaceof the cutting member. The surface 21b could even be straight. inlongitudinal profile. In both of thesecases the width of the surface 21bincreases from both ends towards therniddle of said surface 21. Each ofthe bridges accordingly difiers in shape from the adjacent ones, so thata transverse section similar to Fig. 4 would apply only to one or twoindividual bridges 7 of Fig. 9, with the remaining bridgesdiifering inshape therefrom by having either a wider surface and accordingly smallerheight at their apex, or a narrowerportion of surface 21b with greaterheight at their apex than the said one or two bridges. 1

' The surface 21c may also extend throughout portion of the length ofthe cutting member 4b which is provided 25 with bars and slots, only theend portion being of full thickness along the center. An especiallynarrow thinned 'portion is shown in Fig. 11, and the end portionslongitudinally immediately adjacent thereto are of full thick 'ness. Inthis embodiment the surface 21c has pointed ends.

I S uch apparatus having a thinned portion within the most effectivehalf of the cutting portion of the shearhead have the followingadvantage: In the shaving process, the outer surfaces of the shearheadare pressed against, or

maintained in contact with, the skin of the person to be shaved and thehair extending through the slots 6 will be cut 0E between the inner.cutting member 9 and the outer cutting member 4 atthelevel of the innersurface of the latter when the,inner cutting member is reciprocated;Thus, to obtain aclose shave, it is desirable that the distance betweenthe outer and the inner surface of the outer cutting member l, that is,the height of the bridges 7, be as small in the cutting region as isconsistent with a sufficient strength of these elements. Where thetransverse section of the outer cutting member is as shown in -Fig.5,'it will .be noted that in the region of the point 20 the heightof thebridges7-is greater and accordingly the shave le'ssclose than in otherregions, although such increased height of the bridges 7 is notnecessary to give 59 the bridge its'required strength. -Now, due to theobtuse angle'at which the two surfaces 19 are situated, the edge 29 insuch transverse section as shown in Fig. 5 is the point. at which theskin is'best'tensioned and applied to the shearhead so that the optimumshave wiil occur at this point. if therefore the shave is not closeenough at this point, it will be difficult for the user to obtain acloser shave at all. This drawback is overcome according to .theinvention by providing on at least part of the length of the shearhead,an outer surface 21a, 21b or 210 which 60 is at a smaller distance fromthe inner surfaces 17 or their intersection 18 than the edge 20 wouldbe. The provision of this surface 21 thus materially improves thecloseness of the shave. In the embodiment represented in Fig. 4 thedistance between said surface 21a and the edge 7 .18 is thesame asthethickness of the bridges between the inner and outer surfaces 17 and 19respectively, measured perpendicularly to said surfaces, so that theprovision of surface 2 1a will not affect the strength of the bridges 7;In-fact, it may even be admissible to have atthis pointa smallerthickness of material than in the adjacent regions,.so that the. surface21a may still be .set alittledeepier. Q .Q

Regarding Figs. 6m 8, it will be noted that the provision of roundededges 22 in the region of the outersurfaces 19 favours the bulging ofthe skin into the slots 6,

whereby the shave will be substantially closer than if the skin weretensioned fiat over the surfaces 19. If, however, this desirable bulgingof the skin were also favoured by rounded edges in the region of thesurface 21a, that is, in the thinned portion in which the height of thebridges 7 is reduced and the tension of the skin over the apex of theshearhead is increased, the skin might bulge at this point beyond theinner surface 17 of the outer cutting member 4, become engaged with theteeth 12 of the inner cutting member 9 and be injured or irritated bythem. This is avoided by the provision of the sharp edges 24 of theouter surface 21a, a feature which tends to reduce the bulging of theskin into the slots 6.

Although the intermediate outer surface 210 may be extended to the fulllength of barred portion of the shearhead without departing from thescope of the invention, the provision of end portions not provided withsuch intermediate surfaces as shown in Figs. 2 and 9 has the advantagethat it ensures some additional tensioning of the skin in a longitudinaldirection between such end portions, and accordingly a better shave inthe region of the surface 21:: and 21b, that is, in the thinned portion.

As shown in Fig. 10, the shaving apparatus may comprise three shearheads26, 27 and 28, the two outer shearheads 26 and 28 having no surfaces 21,that is, also no thinned portion, and the middle shearhead 27 havingsuch a surface 21 as described with reference to Figs. 1 to 8. Thisarrangement ensures that the skin is tensioned in transverse directionbetween the shearheads 26 and 28, and in longitudinal direction betweenthe end portions of the shearhead 27 so as to receive its optimumshaving in the central portion of the latter.

It will be observed that a feature common to all the embodiments is thatin each case the shearhead has a thinned portion 21a, 21b or 210 whichprovides for close shaving while immediately adjacent the thinnedportion, in the longitudinal direction of extent of the shearhead, theshearhead wall is thicker and stronger, thus providing strength for theouter cutter immediately adjacent the thinned portion.

Preferably the thickness of the thinned portion within the mosteifective half of the cutting portion of the outer cutting member isless than 0.05 mm. While its breadth preferably does not exceed /3 ofthe breadth of the mentioned most efiective portion of the cuttingportion.

Of course the described thinned portion could also be provided on roundshearheads.

I claim:

1. In combination in a mechanical shaver, a shearhead having alongitudinally extending outer cutter member curved convexly in itslongitudinal direction, an inner cutter member within said outer cutterand movable relative thereto, the outer surface of said outer cutterhaving a central elevated portion extending longitudinally along thecurved periphery thereof and which in use presses more strongly againstthe surface shave than the rest of said outer surface and constitutesthe most effective shaving portion, said elevated portion provided witha plurality of openings extending therethrough, providing a plurality oflongitudinally spaced cutting portions, a part of said elevated portionsof said outer cutter member being of less thickness than other spacedportions thereof located immediately adjacent thereto in thelongitudinal direction of extent of said outer cutter member wherebysaid part of less thickness produces close shaving and said otherlongitudinally adjacent parts provide strength to the outer cuttermember.

2. A shaver according to claim 1 and in which said openings are slotsprovided between transversely extending cutter bars, and the elevatedportion of said outer cutter member is constituted by the centralportions of the said bars.

References Cited in the tile of this patent UNITED STATES PATENTS2,036,557 Viall et al. Apr. 7, 1936 2,266,884 Martin Dec. 23, 19412,281,841 Holsclaw May 5, 1942 2,300,140 Tepas et al. Oct. 27, 19422,331,274 Martin Oct. 5, 1943 2,416,094 Gray Feb. 18, 1947 2,559,772Kobler et al. July 10, 1951 2,562,104 Kobler et al. July 24, 1951FOREIGN PATENTS 147,119 Austria Oct. 10, 1936 469,782 Great Britain Aug.3, 1937

